JP2000057962A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the strain stress developed in welding by providing a cutout near a welding point of a negative electrode and a negative electrode eyelet welded to the cylindrical negative electrode at plural welding points and for holding the negative electrode. SOLUTION: A negative electrode eyelet 37 is formed into a stepped cylindrical shape, and the inner diameter of a small diameter part 40 is formed at a dimension capable of generating about 0.02-0.05 mm of clearance between a negative electrode cylinder 36 in consideration of the structural error and the assembling error of the negative electrode eyelet 37 and the negative electrode cylinder 36. The negative electrode eyelet 37 is welded to the negative electrode cylinder 36 at three welding points 41 for equally dividing (with an angle at 120 degree) a cylinder of the small diameter part 40, and two cutouts 42 are provided near each welding point 41 in both sides of each welding point 41 along the center axis of the negative electrode eyelet 37 from a small diameter part 40 side end (one end). Depth of this cutout 42 from the small diameter part 40 side end is formed larger than a distance from the small diameter part 40 side end to the welding point 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube such as a color picture tube, and more particularly to a cathode ray tube having an electron gun in which a cathode is held by a cathode eyelet.

[0002]

2. Description of the Related Art Generally, a cathode ray tube generates an electron beam emitted from an electron gun disposed in a funnel-shaped funnel neck constituting a vacuum envelope by a deflection yoke mounted outside the funnel. The image is displayed by horizontal and vertical scanning of a phosphor screen provided on the inner surface of a panel constituting a vacuum envelope together with a funnel by being deflected by a horizontal and vertical deflection magnetic field.

In particular, in a color picture tube, an electron gun that emits three electron beams is used. The three electron beams are concentrated on a phosphor screen, and the three electron beams are deflected by a horizontal and vertical deflection magnetic field generated by a deflection yoke. It is formed in a structure that displays a color image by scanning the body screen horizontally and vertically. Such a color picture tube,
At present, the electron gun is of an in-line type that emits three electron beams arranged in a line passing through the same horizontal plane, and the three electron beams arranged in a line are deflected by a pincushion type horizontal deflection magnetic field generated by a deflection yoke and a barrel type vertical deflection magnetic field. By doing so, a self-convergence in-line type color picture tube which concentrates on the entire surface of the phosphor screen without requiring special circuit correction has become mainstream.

In such a cathode ray tube electron gun, in the case of a monochrome cathode ray tube, one cathode structure, a heater for heating the cathode, and a plurality of electrodes sequentially arranged in the fluorescent screen direction from the cathode structure. Are formed integrally with the insulating support rod. For a monochrome cathode ray tube electron gun, a color picture tube
In particular, in a self-convergence in-line type color picture tube, the three cathode assemblies are arranged in a line at equal intervals in the horizontal direction. Are formed in a structure in which a plurality of electrodes of an integral structure are arranged adjacent to each other.

As shown in FIG. 6, the cathode structure includes a cylindrical cathode sleeve 1, a base metal 2 attached to one end of the cathode sleeve 1, an electron emission layer 3 provided on the base metal 2, The strap 4 attached to the cathode sleeve 1 and the cathode sleeve 1
A cathode formed of a cylindrical cathode cylinder 5 coaxially disposed outside the cathode cylinder, and a cathode eyelet 6 attached to the outside of the cathode cylinder 5. A cathode support strap (not shown) is provided on the outer surface of the cathode eyelet 6. ) Is attached, and is formed in a structure supported by the insulating support rod via the cathode support strap. Conventionally, the cathode eyelet 6 is formed in a stepped cylindrical shape, and is welded to the cathode cylinder 5 at three welding points 8 that equally divide the circumference of the small diameter portion 7 (120 ° intervals).

An electron gun of a cathode ray tube requires extremely high assembling accuracy. In particular, the distance (G 1 / K) between the cathode and a first grid (control electrode) adjacent to the cathode and the inclination of the cathode with respect to the axis of the electron gun. Has a great influence on the characteristics and quality of the cathode ray tube. In particular, the mounting accuracy of the cathode eyelet 6 with respect to the cathode greatly affects its G1 / K and the inclination of the cathode.

In general, in the case of an in-line type color picture tube having three cathode structures, it is necessary to make the cutoff voltage the same in order to improve the image quality, and the cathode current (Ik) of each cathode is constant. Designed to be value. Further, it is designed so that the electron beam emitted from each cathode passes through a predetermined position of the main lens portion formed by each electrode.

However, since the cut-off voltage of the actually manufactured electron gun is not always the same, after manufacturing the color picture tube, the bias voltage is adjusted according to the characteristics of each cathode, and Ik is made the same. I have. However, if G1 / K greatly deviates from the design value, the predetermined Ik and luminance cannot be obtained. In addition, when the electron beam trajectory does not pass through the predetermined position of the main lens portion, the beam spot is distorted over the entire screen, and an asymmetric halo occurs, thereby deteriorating the image quality.

Such a problem occurs not only in an in-line type color picture tube but also in an electron gun of a monochrome cathode ray tube.

The reason why the above problem occurs can be explained as follows.

That is, assuming that the central axes of the cathode and the cathode eyelet 6 coincide with each other and that the cathode and the cathode eyelet 6 have no inclination (see FIG. 6), the cathode and the cathode eyelet 6 are located between the cathode cylinder 5 and the cathode eyelet 6. In consideration of a manufacturing error and an assembly error of the cylinder 5 and the cathode eyelet 6, the gap 5 is formed to have a gap g of about 0.02 to 0.05 mm.

For welding such a cathode cylinder 5 and a cathode eyelet 6, as shown in FIG. 9, a collet electrode 10 is inserted into the cathode cylinder 5 previously attached to the cathode sleeve 1 via the strap 4, and The air in the cathode is sucked so that the cathode cylinder 5 can completely enter the tip of the collet electrode 10 from the gap between the collet electrode 10 and the enlarged diameter rod 11 inside the collet electrode 10. Expanding rod 1 so that the centers match
The collet electrode 10 is expanded in diameter by 1 and pressed against the inner surface of the cathode cylinder 5 to fix the cathode. On the other hand, a counter electrode (not shown) is provided on the outer surface of the small-diameter portion 7 of the cathode eyelet 6.
Is brought into contact with each other to bring the welded portion between the cathode cylinder 5 and the cathode eyelet 6 into close contact, and then a welding current is applied between the collet electrode 10 and the counter electrode.

According to such a welding method, the cathode can be fixed without being deformed. However, the cathode cylinder 5
Since there is a gap g of the above-mentioned size between the electrode and the cathode eyelet 6, the welding point 8 of the cathode and its vicinity are deformed, and a distortion stress is generated by this deformation and subsequent welding. Among these strain stresses, the strain stress in the radial direction balances with each other because the three welding points 8 are located at positions where the circumference of the cathode cylinder 5 is equally divided. And as a stress that causes the coaxiality of the cathode eyelet 6 to be deviated or causes inclination, and remains in the cathode cylinder 5 and the cathode eyelet 6,
Heating in the cathode ray tube manufacturing process causes a change in G1 / K and tilts the cathode, thereby deteriorating image characteristics.

That is, the cathode ray tube is manufactured through processes such as exhaustion, activation of the cathode, getter flash, aging of the cathode, and withstand voltage treatment after the electron gun is sealed in the neck. In the activation and aging processes, the cathode is heated by energizing a heater. In this case, when the heater is energized at the rated voltage, the point a on the electron emission layer 3 shown in FIG. 6 is heated to about 800 ° C., and the weld b between the cathode cylinder 5 and the cathode eyelet 6 is heated to about 350 ° C. Is done. Particularly, in the aging step, a voltage of about 160% of the rated voltage is applied to the heater, and at the point a, about 130% of the rated voltage is applied.
It is heated to 0 ° C. and about 600 ° C. at the weld b. Therefore, the cathode cylinder 5 and the cathode eyelet 6 are annealed by the high-temperature heating, causing a change and inclination of G1 / K, thereby deteriorating image characteristics.

[0015]

As described above, the cylindrical cathode cylinder constituting the cathode and the cylindrical cathode eyelet welded to the cathode cylinder are between about 0.02 and 0.05 mm between them. Is formed in a dimension that allows for a gap. Therefore, when a cathode eyelet is welded to the cathode cylinder, stresses that cause the cathode cylinder and the cathode eyelet to be misaligned or cause tilting remain, and the heating of the heater during activation or aging of the cathode in the cathode ray tube manufacturing process. As a result, G1 / K fluctuates or tilts, deteriorating image characteristics.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and reduces the strain stress generated when a cathode and a cathode eyelet are welded to thereby reduce the variation in the distance between the cathode and the first grid. It is another object of the present invention to configure a cathode ray tube having good image characteristics by reducing the inclination of the cathode and the cathode.

[0017]

Means for Solving the Problems (1) A cathode structure constituting an electron gun comprises a cathode formed of a cylindrical part, and a cylindrical cathode eyelet which is welded to the cathode at a plurality of welding points and holds the cathode. In the cathode ray tube, a notch was provided near the welding point of the cathode eyelet with the cathode.

(2) In the cathode ray tube of (1), the cathode eyelets are provided on both sides in the circumferential direction of the cathode eyelet with the welding point of the notch and the cathode interposed therebetween.

(3) In the cathode ray tube of (1), a notch is provided on one side in the same circumferential direction of the cathode eyelet with respect to a welding point with the cathode.

(4) In the cathode ray tube according to any one of (1) to (3), a notch is provided at one end of the cathode eyelet, and the length of the notch from this one end is measured from one end to the welding point. Greater than the distance.

(5) In the cathode ray tube of (1), a notch is formed on one side in the same circumferential direction of the cathode eyelet with respect to a welding point with the cathode, and on one end of the cathode eyelet with respect to the welding point. Provided continuously in the circumferential direction.

(6) In the cathode ray tube of (1), the notch is formed on one side in the same circumferential direction of the cathode eyelet with respect to the welding point with the cathode, and on one end side of the cathode eyelet with respect to the welding point. It was provided continuously in the circumferential direction on the opposite side.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows an in-line type color picture tube which is one embodiment of the present invention. This color picture tube has an envelope consisting of a panel 20 and a funnel 21 having a funnel shape, and a phosphor screen 22 consisting of a three-color phosphor layer emitting blue, green and red light is provided on the inner surface of the panel 2. A shadow mask 23 is provided inside the phosphor screen 22 so as to face the phosphor screen 22. On the other hand, an electron gun 26 for emitting three electron beams 25B, 25G, 25R is arranged on a neck 24 of the funnel 21. And this electron gun 26
Are deflected by a magnetic field generated by a deflection yoke 27 mounted on the outside of the funnel 21 to scan the phosphor screen 22 horizontally and vertically through a shadow mask 23. , And a structure for displaying a color image.

As shown in FIG. 1, the electron gun 26 includes three cathode assemblies 28B, 28G, 28R arranged in a line in the horizontal direction (X-axis direction), and these cathode assemblies 28B, 28R.
G, 28R, three cathodes 29B, 29G, 29
R, three heaters H for heating the cathode structure 28B,
A plurality of electrodes (only the first, second, and third grids G1, G2, and G3 are shown in FIG. 1) sequentially arranged in the direction of the phosphor screen from 28G and 28R, and these cathode structures 28B and 28G , 28R, heater H, and a plurality of electrodes are integrally held by a pair of insulating support rods 30.

Each of the cathode assemblies 28 (28B, 28G, 2)
8R) is a cylindrical cathode sleeve 3 as shown in FIG.
2. A base metal 33 attached to the end of the cathode sleeve 32 on the first grid side, an electron emission layer 34 provided on a surface of the base metal 33 facing the first grid, and attached to the cathode sleeve 32. A cathode 35 (29B, 29G, 29R) comprising a cylindrical cathode cylinder 36 disposed coaxially outside the cathode sleeve 32 via the strap 35, and attached to the outside of the cathode cylinder 36. As shown in FIG. 1, a cathode support strap 38 implanted on the insulating support bar 30 is attached to the outer surface of the cathode eyelet 37.

As shown in FIG. 3, the cathode eyelet 37 is formed in a stepped cylindrical shape, and the inner diameter of the small-diameter portion 40 is determined in consideration of manufacturing errors and assembly errors of the cathode eyelet 37 and the cathode cylinder. As shown in FIG. 2B, a gap g of about 0.02 to 0.05 mm is formed between the cathode cylinder and the cathode cylinder. The small diameter portion 40 is welded to the cathode cylinder 36 at three welding points 41 that equally divide the circumference (120 ° intervals).

Particularly, in this embodiment, two notches are formed along the central axis of the cathode eyelet 37 from the end (one end) of the small-diameter portion 40 near each welding point 41 with the welding point 41 interposed therebetween. 42 are provided. The small diameter portion 4 of the notch 42
The depth d1 from the end on the zero side is formed larger than the distance d2 from the end on the side of the small diameter portion 40 to the welding point 41.

The welding between the cathode cylinder 36 and the cathode eyelet 37 is performed in the same manner as in the prior art (see FIG. 7). That is, the cathode cylinder 36 previously attached to the cathode sleeve 32 via the strap 35
Is inserted into the collet electrode, and the air in the cathode is sucked so that the cathode cylinder 36 completely enters the tip of the collet electrode through a gap between the collet electrode and the enlarged rod.
Further, the diameter of the collet electrode is enlarged by a diameter-enlarging rod so that the center of the cathode coincides with the center of the collet electrode, and the collet electrode is pressed against the inner surface of the cathode cylinder 36 to fix the cathode. On the other hand, the counter electrode is pressed against the outer surface of the cathode eyelet 37 so that the welded portion sandwiched between the two notches 42 of the cathode eyelet 37 is brought into close contact with the cathode cylinder 36, and then the gap between the collet electrode and the counter electrode is formed. This is done by passing a welding current through the wire.

As described above, two notches 42 are formed in the cathode eyelet 37 with the welding point 41 between the cathode cylinder 36 and the cathode cylinder 36 interposed therebetween.
Is provided, the weld between the two notches 42 has a gap between the cathode cylinder 36 and the small-diameter portion 40 of the cathode eyelet 37. , A strain stress is generated, but the strain stress is limited between the two notches 42 and does not extend beyond the notches 42 to the circumferential direction of the cathode eyelet 37. Moreover, since the depth d1 from the end of the notch 42 on the side of the small diameter portion 40 is formed larger than the distance d2 from the end of the notch 42 on the side of the small diameter portion 40 to the welding point 41, the distortion of the cathode eyelet 37 in the central axis direction is reduced. Stress is also limited between the two notches 42. As a result, the strain stress generated in the cathode eyelet 37 is only in the radial direction. However, this radial strain stress is balanced by welding at a position where the circumference of the small diameter portion 40 is equally divided, and the unbalance that causes the concentricity of the cathode and the cathode eyelet to be deviated or causes a tilt as in the related art. Leaves no stress.

Therefore, as described above, the cathode structure 28B
, 28G and 28R, these cathode structures 28B
, 28G, and 28R are assembled into a color picture tube, and the cathode H is heated by the heater H in the activation and aging processes of the cathodes 29B, 29G, and 29R performed when the color picture tube is manufactured. , G1 / K
And a color picture tube which does not deteriorate the image characteristics by eliminating the fluctuation and inclination of the color picture tube.

Next, another embodiment will be described.

The cathode assembly shown in FIG. 5 is particularly close to the small diameter portion 40 of the stepped cylindrical cathode eyelet 37 and only one side in the same circumferential direction with respect to the welding point 41 with the cathode cylinder 36. The notch 42 is provided. This notch 4
2, the depth from the small-diameter portion 40 side end is formed larger than the distance from the small-diameter portion 40 side end to the welding point 41, like the notch in the above embodiment.

The other structure is the same as that of the above-described embodiment, and the same parts are denoted by the same reference numerals and description thereof will be omitted.

In the case where the notch 42 is provided on one side in the same circumferential direction with respect to the welding point 41, when the notch 42 is brought into close contact with the cathode cylinder 36 by pressing with the counter electrode,
The welded portion of the cathode eyelet 37 is deformed and generates a strain stress.
2, it does not extend beyond the notch 42 to the circumferential direction of the cathode eyelet 37. However, it extends in the circumferential direction on the other side where the notch is not provided. But,
Since this strain stress is in the same direction at the three welding points 41, it does not become an unbalanced stress.

The strain stress in the central axis direction of the cathode eyelet 37 is also greater than the distance from the end of the notch 42 to the welding point 41 from the end of the notch 42 to the small diameter portion 40. Since it is formed, it is reduced as compared with the conventional cathode eyelet. As a result, there is no unbalanced stress that causes the cathode and the cathode eyelet to be out of alignment or tilt as in the related art, and a color picture tube that does not deteriorate image characteristics can be configured.

In the above embodiment, one notch is provided on each side in the circumferential direction of the welding point of the cathode eyelet with the cathode cylinder, or one notch is provided on one side in the same circumferential direction. The notches may be provided in two or more in parallel.

The cathode assembly shown in FIG. 6 has a small diameter portion 40 of a stepped cylindrical cathode eyelet 37, one side in the same circumferential direction as a welding point 41 with the cathode cylinder 36, and a welding point 41. The small diameter portion 40 of the cathode eyelet 37
L-shaped notch connected continuously in the circumferential direction opposite to the side end
2 is provided.

The other configuration is the same as that of the above-described embodiment, and therefore, the same portions are denoted by the same reference characters and description thereof will be omitted.

Even when the notch 42 is formed in an L-shape in this manner, if the notch 42 is pressed into contact with the counter electrode and brought into close contact with the cathode cylinder 36, the welded portion of the cathode eyelet 37 is deformed and strain stress is generated. , Its strain stress is the welding point 41
Since the notch 42 is provided in one side direction, the notch 42 does not extend beyond the notch 42 to the circumferential direction of the cathode eyelet 37. However, it extends in the circumferential direction on the other side where the notch is not provided. However, this strain stress is caused by three welding points 4
For No. 1, since the directions are the same, there is no unbalanced stress.

As a result, there is no unbalanced stress that causes the cathode and the cathode eyelet to be out of alignment or causes inclination, and a color picture tube that does not deteriorate image characteristics can be constructed.

The cathode assembly shown in FIG. 7 has a small diameter portion 40 of a stepped cylindrical cathode eyelet 37, one side in the same circumferential direction as a welding point 41 with the cathode cylinder 36, and a welding point 41. The small diameter portion 40 of the cathode eyelet 37
A notch 42 is provided in a U-shape so as to be continuous in the circumferential direction on the side end side and the opposite side.

Other structures are the same as those of the above-described embodiment, and the same parts are denoted by the same reference numerals and description thereof will be omitted.

Even when the notch 42 is formed in an L-shape as described above, if the opposed electrode is pressed against and brought into close contact with the cathode cylinder 36 and welded, the welded portion of the cathode eyelet 37 is deformed and strain stress is generated. , Its strain stress is the welding point 41
Since the notch 42 is provided in one side direction, the notch 42 does not extend beyond the notch 42 to the circumferential direction of the cathode eyelet 37. However, it extends in the circumferential direction on the other side where the notch is not provided. However, this strain stress is caused by three welding points 4
For No. 1, since the directions are the same, there is no unbalanced stress.

As a result, there is no unbalanced stress that causes the cathode and the cathode eyelet to be out of alignment or causes inclination, and a color picture tube that does not deteriorate image characteristics can be constructed.

In the above embodiment, an electron gun of an in-line type color picture tube has been described. However, the present invention relates to an electron gun of a color picture tube other than the in-line type color picture tube or an electron gun of a monochrome cathode ray tube. The same effect can be obtained by applying

[0047]

As described above, if a notch is provided in the vicinity of the welding point of the cathode eyelet holding the cathode with the cathode cylinder, even if the cathode cylinder and the cathode eyelet are welded, the cathode and the cathode remain in the conventional manner. The unbalanced stress that causes the eyelet to be out of alignment or tilting is eliminated, and G1
It is possible to configure a color picture tube which does not cause deterioration of the image characteristics due to the fluctuation or inclination of / K.

[Brief description of the drawings]

FIG. 1A is a horizontal sectional view showing a main part of an electron gun of an in-line type color picture tube according to an embodiment of the present invention, and FIG. 1B is a vertical sectional view. .

FIG. 2A is a front view partially showing a cross section of a cathode structure of the electron gun, and FIG. 2B is a cross-sectional view taken along the line BB.

FIG. 3 is a front view of a cathode eyelet constituting the cathode assembly.

FIG. 4 is a diagram showing a configuration of an in-line type color picture tube which is an embodiment of the present invention.

5 (a) is a front view of a different cathode structure, FIG.
(B) is the BB sectional view.

FIG. 6A is a front view of another different cathode structure, and FIG. 6B is a cross-sectional view taken along the line BB.

FIG. 7A is a front view of another different cathode structure, and FIG. 7B is a cross-sectional view taken along the line BB.

8 (a) is a front view showing a partial cross section of a cathode structure constituting an electron gun of a conventional in-line type color picture tube, and FIG. 8 (b) is a BB cross section thereof.

FIG. 9 is a view for explaining a method for welding the cathode and the cathode eyelet of the conventional cathode assembly.

[Explanation of symbols]

 26 ... Electron gun 28B, 28G, 28R ... Cathode assembly 29B, 29G, 29R ... Cathode 32 ... Cathode sleeve 36 ... Cathode cylinder 37 ... Cathode eyelet 41 ... Welding point 42 ... Notch

Claims (6)

[Claims] 1. A cathode ray tube comprising a cathode in which a cathode structure constituting an electron gun is formed of a cylindrical part, and a cylindrical cathode eyelet which is welded to the cathode at a plurality of welding points and holds the cathode. A cathode ray tube, wherein a notch is provided near a welding point of an eyelet with a cathode. 2. The cathode ray tube according to claim 1, wherein the notches are provided on both sides of the cathode eyelet in the circumferential direction with respect to a welding point with the cathode. 3. The cathode ray tube according to claim 1, wherein the notch is provided on one side in the same circumferential direction of the cathode eyelet with respect to a welding point with the cathode. 4. A notch is provided at one end of the cathode eyelet, and a length of the notch from the one end is larger than a distance from the one end to a welding point. 3. The cathode ray tube according to any one of 3. 5. A notch is provided continuously on one side in the same circumferential direction of the cathode eyelet with respect to the welding point with the cathode and on the opposite side of one end of the cathode eyelet with respect to the welding point. The cathode ray tube according to claim 1, wherein the cathode ray tube is provided. 6. A notch is formed on one side in the same circumferential direction of the cathode eyelet with respect to the welding point with the cathode, and on one end side and on the opposite side of the cathode eyelet with respect to the welding point. The cathode ray tube according to claim 1, wherein the cathode ray tube is provided.